Correct positioning of an annular combustor within the casings of a gas turbine engine is very important, because precise alignment with respect to the injection of fuel, inflow of air and the turbine is required to avoid excessive stresses on combustor components and to aid proper combustion. Incorrect alignment of the combustor increases stresses on combustor components that interface with the turbine nozzle guide vanes, resulting in decreased component life.
A known method of combustor alignment utilizes the principle of cross-key location, shims being used between confronting location faces of the cross-keyed components to enable the making of fine adjustments to combustor alignment. However, to obtain satisfactory alignment of the combustor in this way can be very time-consuming, particularly when the assembled combustor is large and heavy. Several iterations of the alignment procedure may be required, involving the use of several different thicknesses of shims between each set of confronting location faces. Moreover, a completely correct alignment cannot be guaranteed.
Therefore, to save time and reduce costs during manufacturing assembly of an engine and during rebuild of an engine after maintenance actions, it will be advantageous to have a faster and more precise way of obtaining correct combustor alignment.